Código PHP:
<table width="100%" height="100%" border="0" align="center" cellpadding="0" cellspacing="0">
<tr>
<td align="center" valign="middle"><table width="770" border="0" align="center" cellpadding="0" cellspacing="0">
<tr>
<td> </td>
</tr>
</table></td>
</tr>
</table>